In a computing device, which may include devices such as general purpose hand-held computers, gaming devices, communications devices, smart phones, embedded or special-purpose computing systems, memory devices may be utilized to store instructions for use by one or more processors of the computing device. Memory devices suitable for use in at least some types of computing devices may include resistive memory devices, which operate to store binary logic values, such as a binary logic “1” or a binary logic “0,” utilizing resistive states of an appropriate material. In one example, in a resistive memory, a binary logic “1” may be stored responsive to placing the resistive memory element into a relatively high-impedance state. The resistive memory may store a binary logic “0” responsive to placing the resistive memory into a relatively low-impedance state.
When reading binary logic values stored by way of a resistive memory element, a “sense” voltage may be applied at a particular memory address within an array of resistive memory elements. Responsive to a voltage drop, which may form across the resistive memory device after application of a sense voltage, a sense amplifier may be utilized to determine the logic state of the particular resistive memory element. When a binary logic “1” is detected, the sense amplifier may generate a signal comprising a first voltage level. Detection of a binary logic “0” may give rise to the sense amplifier generating a signal comprising a second voltage level. In particular implementations, a reference impedance may be utilized by a sense amplifier to assist in differentiating, for example, a high-impedance state from a low-impedance state of a resistive memory element. Such differentiation may be performed, for example, responsive to performing a comparison between a voltage drop across the resistive memory device and a voltage drop across the reference impedance.
However, in many computing devices, it may be advantageous for an appreciable difference in resistivity to exist between a reference impedance and a high-impedance state as well as between a reference impedance and a low-impedance state. In addition, it may be advantageous for such impedance differences to exist over a significant range of operating temperatures, such as temperatures from below about 0.0° C., to temperatures in excess of about 100.0° C. Accordingly, providing reference impedances, which can be trimmed or tuned to provide particular impedances that enable reliable detection of high-impedance/low-impedance states of a resistive memory elements continues to be an active area of investigation.
Reference is made in the following detailed description to accompanying drawings, which form a part hereof, wherein like numerals may designate like parts throughout that are corresponding and/or analogous. It will be appreciated that the figures have not necessarily been drawn to scale, such as for simplicity and/or clarity of illustration. For example, dimensions of some aspects may be exaggerated relative to others. Further, it is to be understood that other embodiments may be utilized. Furthermore, structural and/or other changes may be made without departing from claimed subject matter. References throughout this specification to “claimed subject matter” refer to subject matter intended to be covered by one or more claims, or any portion thereof, and are not necessarily intended to refer to a complete claim set, to a particular combination of claim sets (e.g., method claims, apparatus claims, etc.), or to a particular claim. It should also be noted that directions and/or references, for example, such as up, down, top, bottom, and so on, may be used to facilitate discussion of drawings and are not intended to restrict application of claimed subject matter. Therefore, the following detailed description is not to be taken to limit claimed subject matter and/or equivalents.